PhysWall

A browser extension that stops AI inventing numbers - by checking them against physics, not against the internet. Nothing is stored. Nothing is sent. It runs in your browser, and it takes a minute to install. A physics engine, and a verification tool enforced on top of it. Physwall inverts a closed, published, non-linear physical law at a single measurement point — and refuses when the inverse is not unique. Seven laws, one engine, and the same refusal in all of them. Roughly a third of what the best AI returns cannot be built. Not suboptimal — impossible, and nothing in the reply says so (that figure is from ConstraintBench, February 2026, across six frontier models: the best of them reached 65% feasibility). Physwall runs inside ChatGPT, Claude, Gemini, Mistral and Meta AI, and underlines the numbers that were collected from the internet but weren't properly checked by a real physics engine. There's no account, and the conversation never leaves the browser.